Propulsive performance analysis of a twin-flapping-foil propulsor based on RANS equations

In this paper, the propulsive performance of a twin-flapping-foil propulsor in ground effect was calculated based on the RANS equations; dynamic mesh method was applied in numerical calculation. The calculation included the effects of the number of foils (single versus double), freestream velocity, flapping frequency and amplitude to the propulsive performance. Numerical calculations showed that the thrust increased with the increasing of flapping frequency and amplitude, but when the freestream velocity or the flapping amplitude increased, the propulsive efficiency increased first and decreased then. The thrust and propulsive efficiency were also compared of single foil with twin foils. This simple thruster can generate thrust perpendicular to the foil’s shaft by flapping without pitching motion, a thruster vector of any direction can be generated by rotating the foils, which can satisfy the thrust requirement of the underwater vehicle in six degree of freedom motion.